Add Flatpak host GL driver support

[orowith2os]

Closes #155

Needs testing to be sure everything works properly. I don't own a NVIDIA GPU, so I can't do it.

You can test by installing, making sure /var/lib/flatpak/extension/org.freedesktop.Platform.GL.host/x86_641.4 exists and is filled with the NVIDIA files, and running FLATPAK_GL_DRIVERS=host flatpak run test.openglorvulkan.app.

[ptr1337]

I don't know if this really should be enabled as default. That will raise the package size.

[orowith2os]

Many people also use flatpak, especially as it makes things Just Work, and several applications only officially support Flatpak for cross-distribution distribution like Bottles and OBS Studio. I think it makes sense to have it enabled by default, especially since using a development NVIDIA driver isn't as easy with Flatpak, which some people might want to do.

If bubblewrap supported making symlinks not dangle inside of a sandbox, I could just symlink these, but I can't, so we can copy them over. Plus, you'd have about the same storage usage as if you used Flatpak like before anyways. I'm not worrying about it.

[Tk-Glitch]

I'm not convinced about having that enabled by default. We got quite a few users who don't want anything flatpak on their machine, so I'd like to keep "Arch-style" packages as the default. Other than that, nice addition ! Thanks for looking into it orowith2os ! 🐸 ❤️

[orowith2os]

This still needs testing, once it's confirmed to work I'm open to disabling it. I'll also add a lil console note for it, since it seems appropriate to mention it there.

[konkitoman]

I cannot run any flatpak application that uses GPU drivers from the latest vulkan dev driver 535.43.22, so i tested this!

On my machine i merged this into master!

To test if the flatpak host driver is installed i run paru -Q flatpak-host-driver-tkg
And the output was flatpak-host-driver-tkg 535.43.22-252

There is no test.openglorvulkan.app
But i tried to run OBS and ATLauncher with FLATPAK_GL_DRIVERS=host flatpak run

OBS message Failed to initialize video. Your GPU may not be supported, or your graphics drivers may need to be updated.
ATLauncher message Failed to find any valid GLFW profile. Trying 4.6: GLFW error: [0x10006]GLX: Failed to load GLX

More info

I removed all flatpak packages that had org.freedesktop.GL in there name but that before i installed this!
flatpak update wants to install the org.freedesktop.GL.default
but FLATPAK_GL_DRIVERS=host flatpak update do not!

There is directories in /var/lib/flatpak/extension/org.freedesktop.Platform.GL.host/x86_64/1.4 and /var/lib/flatpak/extension/org.freedesktop.Platform.GL.host/i386/1.4

But in flatpak list output there is no org.freedesktop.Platform.GL.host!